1. Technical Field of the Invention
The present invention relates to integrated circuits and more particularly to resistors or resistive paths.
2. Description of Related Art
In many electronic applications, active components, such as transistors, are connected to passive components, especially resistors.
It is therefore desirable to produce resistors within an integrated circuit. Such resistors must be able to have a high resistance in order to reduce the current and the energy consumption, in particular in analog applications and/or wireless devices.
Moreover, in the case of voltage regulators, there are two resistors are placed in series at the output of a transistor that have to be particularly well matched in terms of resistance, low-frequency noise and linearity.
Applicants have noticed that when a resistor is formed in a film of a given conductivity type, n or p, surrounded by insulating regions made of amorphous material, for example SiO2, the noise of such resistors is high and liable to vary greatly from one resistor to another.
Applicants believe that this phenomenon is due to a material mismatch between the crystalline material forming the resistor and the amorphous or polycrystalline material of the adjacent insulating regions. Because of the mismatch in the crystal lattice at this point, there are a number of vacancies liable to trap or emit electrons, thus generating noise when an electric current flows. The number of these vacancies depends on the area of the resistor in contact with the insulating region.
The present invention aims to remedy these drawbacks. There is a need in the art to produce a resistor or a resistive path in an integrated circuit that has a low noise, especially at low frequency, has reproducible performance from one resistor to another and, where appropriate, has a high resistance.